Prazosin and captopril in chronic heart failure: comparison of acute haemodynamic and hormonal effects

Comparative hemodynamic and clinical effects of long-term treatment with prazosin and captopril for severe chronic congestive heart failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

Short- and long-term hemodynamic and clinical responses to sequential therapy with prazosin (15 mg/day for 3 to 12 weeks) and captopril (75 to 300 mg/day for 2 to 15 weeks) were compared in 22 patients with severe chronic congestive heart failure. First doses of prazosin produced marked increases in cardiac index and stroke volume index (p less than 0.01), but these effects were lost during long-term treatment. First doses of captopril produced only modest increases in both variables, but these persisted without attenuation during prolonged therapy. Both drugs produced immediate decreases in left ventricular filling pressure, mean arterial pressure, mean right atrial pressure and systemic vascular resistance; these changes became significantly attenuated (p less than 0.01) with prazosin but not with captopril. At the end of treatment, stroke volume index was significantly higher and right and left ventricular filling pressures were significantly lower with captopril than with prazosin (p less than 0.05 to 0.01). Only 8 of the 22 patients (36%) treated with prazosin benefited clinically, whereas 14 of 19 patients (74%) treated with captopril felt that they had improved (p less than 0.05). These differences could not have been predicted by comparing responses to first doses of the 2 drugs. These findings indicate that the choice of 1 vasodilator drug over another in patients with congestive heart failure should be based on studies that compare their long-term rather than short-term hemodynamic and clinical effects.

Enalapril in patients with chronic heart failure: a placebo-controlled, randomized, double-blind study

A number of studies have shown short-term hemodynamic and symptomatic improvement in patients with congestive heart failure treated with angiotensin converting-enzyme inhibitors. The long-term efficacy of the oral long-acting converting-enzyme inhibitor enalapril remains to be established in controlled studies. We evaluated this drug in 36 patients with New York Heart Association functional class II to III heart failure who were clinically stable on digoxin and diuretic therapy. After baseline assessment of symptoms, exercise capacity, and results of echocardiographic examination and right heart catheterization, patients were randomly assigned to treatment with 5 mg enalapril twice daily (n = 18) or placebo (n = 18) in a double-blind fashion. The two groups had similar clinical, echocardiographic, and hemodynamic characteristics before treatment. After 3 months of treatment, the enalapril group showed a significant improvement as judged by subjective patient impression, functional class, and exercise duration (9.3 +/- 5.7 vs 17.6 +/- 5.6 min; p less than .001). Diuretic dosage was reduced in six patients and increased in one patient, one patient had died and another had been withdrawn from the study. In the placebo group there was no significant change with respect to patient impression, functional class, or exercise duration; diuretic dosage was increased in seven patients and four patients had died. Echocardiographic left ventricular dimensions were significantly reduced and left ventricular shortening fraction significantly increased in the enalapril group but were unchanged in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic effects of captropril in chronic heart failure: efficacy of low-dose treatment and comparison with prazosin

The acute hemodynamic effects and long-term therapeutic actions of low doses of the oral angiotensin-converting enzyme (ACE) inhibitor captopril (CPT) were evaluated in 18 patients with severe chronic congestive heart failure (CHF). Increasing doses of 1, 2.5, 6.25, 12.5, and 25 mg of CPT were given at 2-hour intervals. Increased stroke volume index (SVI) and reduced mean pulmonary capillary wedge (PCW) pressure occurred at 1 hour (p less than 0.05) with an associated decline of blood pressure. Maximal hemodynamic improvement for the group was seen at 6 and 7 hours following the 6.25 and 12.5 mg doses when SVI was elevated 35% and mean PCW pressure decreased 40% from control. CPT in doses of 12.5 to 50 mg every 8 hours was continued long term in these 18 CHF patients. Four patients died, and one was noncompliant; drug therapy was withdrawn in two patients with symptomatic hypertension and in one patient who experienced an alteration in taste. The remaining 10 patients showed significant improvement in symptoms and treadmill exercise duration at 3 months after CPT therapy was started. Moreover, repeat hemodynamic measurements were similar to optimal measurements obtained during the initial study. In a further study, the acute hemodynamic and hormonal effect of sequentially randomized 5 mg prazosin and 25 mg CPT were compared in 10 CHF patients. While both drugs reduced PCW pressure and vascular resistance, CPT effects were greater. Further, CPT alone effected a small rise in cardiac index and minor decline in heart rate, and CPT diminished aldosterone levels and increased plasma renin activity while prazosin did not.